The present invention is directed to a building system especially useful in off-site, factory built structures including manufactured and modular constructions as well as in recreational vehicles, panelized housing and other buildings that are transportable from the manufacturing location to a final site of more or less fixed location. The present invention is particularly directed to a chassis system to be employed in the construction and transport of the structure. The invention is also directed to a floor system to be used in cooperation with the chassis that provides important advantages. The invention is also directed to an integrated lifting system for the structure so that the structure can be installed easier, safer, with less labor, and with less opportunity for damage.
Conventional off-site factory built structures are typically built on a chassis constructed of a pair of spaced, parallel longitudinal steel I-beams running the length of the structure. A floor is generally constructed of a plurality of floor joists laterally arranged with respect to, and supported by, the longitudinal steel I-beams. Outriggers are fixed to the parallel longitudinal I-beams and extend laterally outward from the outer sides of the I-beams to support the outer walls of the structure. A running gear is attached to the longitudinal I-beams near one end of the structure, while a towing hitch is coupled to the opposite end of the longitudinal I-beams so as to allow the structure to be transported from the manufacturing location to the final site of installation or use. At the installation site, a support structure is generally employed to support the I-beams of the off-site factory built unit. This support structure typically takes the form of plurality of piers or posts located in a crawl space, with the piers or posts directly underlying the I-beams. Where two or more such units are used to construct a single building, multiple rows of piers are required for the supporting structure. Illustrative examples of such construction and support can be found in U.S. Pat. Nos. 3,042,423; 3,830,024; 4,131,301; 4,232,884; 4,517,781; and 5,353,558.
In many situations, it would be desirable to locate an off-site factory built unit of this type over a basement instead of a crawl space. A supporting structure in the form of rows of piers is not an acceptable feature in a conventional basement. Instead it is desirable to have a perimeter support, possibly augmented with a limited number of central supports for multiple unit structures. To achieve a perimeter support for structures of this type, additional cross beams can be added that increase the depth of the cavity, or the plurality of outriggers that are fixed to the parallel I-beams are strengthened and secured to the I-beams sufficiently to permit the load transfer. In this manner the floor load that is carried by the I-beams is transferred to the perimeter of the structure so that it can be supported by a foundation or basement wall, longitudinal center post beam, or the like as disclosed in U.S. Pat. Nos. 4,971,355; 5,579,622; 5,640,814; 5,784,849; and 6,044,610. While this solution improves the space utilization for any basement, the placement of any stairwell to that basement remains restricted. The longitudinal I-beams remain as the principal load support for the floor and cannot generally be cut to allow for the placement of a stairwell across that portion of the floor structure. While a lateral beam structure as disclosed in U.S. Pat. No. 4,027,439 can be employed, the added vertical height of the system is significant, and the added cost sufficiently prohibitive that the solution is rarely used.
What is needed is a system for constructing off-site factory built structures that eliminates the need for the metal longitudinal I-beams and outriggers, and provides substantial support for the floor of the structure on a perimeter support so that a conventional basement wall or foundation can be employed to support the structure at its final location, and a stairwell can be inserted at virtually any desired location. What is further needed is a chassis and floor construction of minimum vertical height, which will reduce the required stair run length for stairways associated with the building, and facilitate use of the structures in two-story systems. What is additionally desired is a chassis and floor construction that will permit removal of any running gear once the unit has be situated on the perimeter support. What is additionally desired is a system that will facilitate the installation of the off-site factory built structure on the perimeter support.